Remedial Construction Research Articles

Dam and Levee Safety Risk during Remedial Construction

Abstract Structural modifications to dams and levees can create life safety risks during the construction period. It is important for all parties involved to understand the potential risk, evaluate methods to mitigate risk, and consider the risk when making decisions. Most importantly, it is critical to always strive to “do no harm” and prevent activities that could potentially increase risk. This case history will provide examples of conditions that can lead to increased risk during construction including excavations that lower the crest of a dam or levee, excavations at the toe of an embankment, rapid embankment construction, blocked bypass tunnels, spillway modifications, excavations for outlet culverts, and damage from grouting. A key component of many construction projects is a temporary cofferdam to protect the work area from flooding. Cofferdams have a high potential to create risk during construction. An important step to help prevent increasing risk during construction is to have multiple constructability reviews during the development of the project design. If the potential for construction risk is properly identified, the risk can often be mitigated or reduced. Decision-maker involvement is necessary to assure risks are understood and proper decisions can be made. Several case histories are presented to demonstrate how risks during remedial construction are evaluated and incorporated into decision-making.

Comprehensive study on green and sustainable remediation in the USA: policy system and case experiences

The implementation of green remediation or sustainable remediation (collectively referred as green and sustainable remediation, GSR) has been promoted by multi-stakeholder collaboration. However, comprehensive analysis of GSR is understudied in previous literatures. Policy system and case experience of GSR in the USA are here been analyzed comprehensively. Results indicate that USEPA, SURF-US, and ITRC advocated GR, SR, and GSR, respectively. For the program types of GSR cases, the government-driving forces (especially USEPA) had significant positive effects than those voluntary cleanups. In situ techniques of soil remediation are more widely used than ex situ ones. All techniques of groundwater remediation are in situ, in addition to pump and treat due to its effectiveness to remedy seriously contaminated sites. The best management practices (BMPs) are preferably implemented in remedial construction stagerather than other stages. The percentages of BMPs related to "optimization," "renewable energy," and "recycling or reusing materials" are relatively high, while the other BMPs are relatively low. GSR benefits achieved by BMPs of environment-orientated may not only reduce the environmental footprint, but also gain in economic and social aspects. Moreover, practitioners should more fully understand the full benefits of a BMP implementation and strengthen the consensus among them. In brief, it is necessary for remediation practitioners to supplement the existing defects in policies and their implementations and to select optimum BMPs in specific contaminated sites. This work offers comprehensive and valuable insight into policies and practices of GSR.

Gowanus Canal Superfund Site. III: Leaching of In Situ Stabilization/Solidification Mix Designs

An in situ stabilization/solidification (in situ S/S or ISS) field pilot was conducted in the Gowanus Canal on the manufactured gas plant (MGP) impacted sediments using 9 mix designs including 5%–10% by dry weight (wt%) type I/II Portland cement (PC), type V PC, and NewCem (NC) slag cement in various combinations. Naphthalene was the primary contaminant with total contents between 187 and 54,500 mg/kg and a median value of 1,320 mg/kg. A mobile nonaqueous phase liquid (NAPL) was observed in many of the untreated sediment samples. USEPA 1316 testing modified (M) for organics showed that 7 out of 9 untreated samples had naphthalene effective solubilities on the order of 11.5–14 mg/L and its leaching was solubility controlled. Leaching of S/S-treated samples using USEPA 1315M was completed using polydimethylsiloxane (PDMS) liner inserts and in both deionized (DI) and saltwater (SW) baths to compare the impact of simulated brackish conditions (approximately 22.4 g/L salt) on the leaching of volatile organic compounds (VOCs). The main differences were that the pH of the DI water bath was approximately 3–3.5 units higher than the SW bath but the conductivity of the latter was typically 30–50 times greater. Visible crusts were observed on all SW bath samples, the most significant crusts being associated with the lowest VOC leaching rates. Dissolved organic carbon (DOC) leaching was relatively unaffected by bath type. The naphthalene percent leaching reductions (% LRs) for the top five mixes (> 97% LRs) versus the untreated sediment were 5%–14% higher under SW conditions, presumably due to the surface crusts. The interval mass releases from the top 3 mixes under SW conditions were approximately100 times lower than the corresponding DI water bath values. Because 3 out of the top 5 mixes were the 60/40 (w/w) type V PC/NC blend, a minimum dose of 7.5 wt% of this blend was recommended for remedial construction.

Epidemiology and control measures of an OXA-48-producing Enterobacteriaceae hospital outbreak

SummaryCarbapenemase-producing Enterobacteriaceae (CPE) are a significant challenge to healthcare and infection prevention and control teams. In the UK, OXA-48-like carbapenemases are frequently reported. We describe an outbreak of OXA-48-like producing Enterobacteriaceae and the control measures that proved effective in containing further spread.AimTo describe epidemiologic and laboratory features of outbreak and highlight key control interventions.FindingsFollowing the introduction of an increased sensitivity CPE screening protocol, OXA-48-like CPE were identified in screening and clinical samples from 96 patients across five hospital wards between November 2017 and July 2018. Klebsiella pneumoniae and Enterobacter cloacae were the most frequently isolated organisms, although a range of OXA-48-like positive organisms were identified. The outbreak was contained utilising certain key interventions, including the modification of laboratory screening processes, engagement of hospital senior management, clear and frequent communication and a strong ‘ward presence’ by the infection prevention and control team (IPCT).ConclusionOur report describes how a change in laboratory CPE screening process unmasked a CPE outbreak. The range of bacterial species harbouring the OXA-48-like mechanism suggested plasmid-mediated transfer of resistance. The timely implementation of interventions using a clinical, ‘ward-based’ approach to infection prevention and control highlights the importance of behavioural change in infection control interventions and enabled the termination of a large outbreak without recourse to environmental sampling, major remedial construction work or extensive molecular strain or plasmid typing.

A case study on the plan for soil reinforcement by TCS in south korea

Compaction grouting was developed in the 1950s as a remedial measure for the correction of building settlement, and used almost exclusively for that purpose for many years. Over the past 25 years, however, compaction grouting technology has evolved to treat a wide range of subsurface conditions for new and remedial construction. Compaction grouting is used foundation rehabilitation, ground improvement, railroad subgrade stabilization, seismic/liquefaction mitigation, sinkhole remediation, tunneling stabilization, void filling. It also has merit that makes possible to construct structures having narrow working spaces. But the effects of ground improvement depending on the type of soil must be studied in order to adopt in various soil(granular soil and cohesive soil). In this paper, field and laboratory tests were performed to understand effects of ground improvement for soft ground and seismic mitigation. To know the characteristics of bearing capacity in adjacent ground, plate loading test for behind the improving ground. Strength characteristics of TCS were indicated by uniaxial compression test. Ground improvement effect by TCS together strength increment effect by TCS itself was proved that TCS can be used for soil improvement method using bearing capacity increment.

Applying Computer Vision Technology to Triaxial Deformation Monitoring of Remedial Construction for a Landslide

Background & Objective: The paper explores a new instrument of computer vision to measure three-dimension deformation with an Internet of Things (IoT) system including Raspberry Pi, digital cameras and OpenCV programs in laboratory and field testing so as to monitor the potential deformation of a structure drainage well in a landslide. Methods: A chessboard pattern is detected in the image by the camera so that pixels of chessboard cornors can be recognized by OpenCV programs. X-direction, Y-direction and Z-distance changes can be casulated by the similar triangles relationship of camera pixels. For laboratory testing, standard deviations of the measurement were approximately 0.01 cm. Results: For field testing, the study installed four sets of Raspberry Pi in a drainage well within a landslide and employed OpenCV programs to interpret pixel changes of chessboards at four levels of the draiage well. Conclusion: Overall, the instrument can be employed for triaxial deformation monitoring of the construction in the field effectively and automatically.

Karstification beneath the Birs weir in Basel/Switzerland: A 3D modeling approach

We present a three-dimensional model describing the evolution of a gypsum karst aquifer along the Birs river near Basel in Switzerland. Here, a small dam-site was built in 1890 to generate hydro-electric power. After subsidence of a nearby highway, geophysical and geological field studies have been carried out and a detailed hydrogeological model has been developed. These observations identified a karstified weathered zone as the reason for the subsidence. To prevent any further damage, remedial construction measures have been carried out. We employ our numerical model KARSTAQUIFER, which simulates the temporal evolution of a karst system by dissolution, increasing the porosity in the aquifer. We used results from geological and geophysical investigations as a priori information for implementing the initial boundary conditions into our three-dimensional numerical model. Our model accounts for topography, precipitation and geology and especially for the anisotropy of the local bedrock. It can successfully reproduce the weathered zone in its current horizontal and vertical extent. We cm also simulate the possible evolution of the aquifer following a remedial construction phase. Therefore, taken together with the geophysical and geological observations and the groundwater model, our three-dimensional karst aquifer evolution model enhances the understanding of the development of this heterogeneous karst aquifer system. (C) 2012 Elsevier B.V. All rights reserved. Hydrogeologie der Nordwestschweiz, Grundwasser

Investigating sediments and rock structures beneath a river using underwater ERT

AbstractThis article presents hydrogeophysical investigations performed in a well-developed, long-term hydrogeological gypsum karst research site where subsurface evaporite dissolution has led to the subsidence of a river dam and an adjacent highway; both constructed on gypsum-containing rock, southeast of Basel, Switzerland. An observation system was set up to improve the protection of surface and subsurface water resources during remedial construction measures of the highway and in order to understand the processes, as well as the temporal evolution, of rock water interaction (flow and dissolution).However, no detailed hydrogeological information beneath the river could be derived from the previous investigations. To supplement the basic knowledge on this area, underwater Electrical Resistivity Tomography (ERT) measurements were conducted in the river bed upstream of the dam. The ERT-data are interpreted together with drill-core information and a conceptual 3D-Model of the area behind the dam and beneath the river. Results help to delineate weathered zones, associated faults and the thickness of sediment deposits behind the dam, as well as to locate voids within the local karst system. The combination of the ERT and modeling allows the optimization of future site-specific remedial construction measures.

Metrics for integrating sustainability evaluations into remediation projects

AbstractThe US Sustainable Remediation Forum (SURF) created a compilation of metrics (Metrics Toolbox) in response to a need for a broad set of metrics that could be used to assess and monitor the effectiveness of remedies in achieving sustainability goals. Metrics are the key impacts, outcomes, or burdens that are to be assessed or balanced to determine the influences and impacts of a remedial action. Metrics can reflect any of the three aspects of sustainability (i.e., environmental, social, or economic) or a combination of these aspects. Regardless, metrics represent the most critical sustainable outcomes from the perspective of the key stakeholders. The Metrics Toolbox is hosted online at www.sustainableremediation.org/library/guidance‐tools‐and‐other‐resources. By selecting metrics from the Metrics Toolbox as a starting point and considering a potentially wider suite of metrics in remedial program decisions, appropriate assessments can be made. Qualitative and quantitative metrics are tabulated for each remedial phase: remedial investigation, remedy selection, remedial design, remedial construction, operation and maintenance, and closure. Attributes for each metric are described so that remediation practitioners and key stakeholders can view the universe of metrics available and select the most relevant, site‐specific metrics for a particular site. For this reason, SURF recommends that remediation practitioners consider the metrics compiled in the Metrics Toolbox as a companion to the sustainable remediation framework published elsewhere in this journal and other sustainability evaluations. © 2011 Wiley Periodicals, Inc.

Integrated investigations of karst phenomena in urban environments

Theories that describe karst systems are often limited to conceptual models. However, engineering projects within complex karst systems demand the development of tools that allow site-specific descriptions of the hydrogeologic settings and calibrating the processes of karst evolution. Subsidence of a river dam and an adjacent highway, both constructed on gypsum-containing rock, southeast of Basel, Switzerland, required remedial construction measures. A monitoring network was set up, to safeguard surface and subsurface water resources during the construction measures. The primary project goal was to develop tools that enable a continuous characterization of the groundwater flow regime and that facilitate the evaluation of the long-term performance of the infrastructures. Investigative methods included high-resolution 3D hydrogeological modeling, and the integration of geological, hydrometrical and hydrogeophysical field data of varying quality. Particular focus was placed on the hydraulic behavior of the complex conduit system. Results help to understand the evolution of distinct karst features and zones of preferential flow. The location of fracture zones and parts of the old meandering river course, playing a major role in the karst evolution process, could be identified. Together with the hydrometrical investigations and hydrogeological modeling, the evolution of the karst system and its dynamics can be interpreted in relation to the groundwater flow regime.

Damage of Reinforced Concrete Structure due to Severe Soil Expansion

In Irbid City, Jordan, foundation designs made before 1983 were based on bearing capacity criteria with a limited knowledge of high shrink/swell soil problems. The use of wide and shallow foundation systems was generally the practice rather than the exception in this area. Lack of structural rigidity and insufficient dead load pressure of the foundation systems used in the Irbid area where soils of high shrink/swell are present often cause serious problems related to the performance of constructed facilities. This paper presents a case study typical of a severely cracked one-story reinforced concrete (RC) building constructed over the expansive clay of Irbid City. The building is founded on a mat foundation (solid RC structural slab) embedded at a shallow depth and bearing directly on expansive clay. It is unfortunate that the high shrink/swell potential of the foundation soil had not been recognized properly in the design stage. Based on field and laboratory investigations, remedial construction for the damaged building was proposed. The proposed remedial construction was performed, and more than 10 months have elapsed since the remedial work was completed, with the performance of the building in perfect condition.

Concepts and Results in the Uranium Mill Tailings Remedial Action Ground Water Project

The U. S. Dept of Energy is responsible for bringing 22 former uranium millsites into compliance with ground water standards determined by the U. S. Environmental Protection Agency. These standards require that contaminants in the ground water not cause an unacceptable risk to human health and the environment. One of three compliance strategies is selected for each site; no further action, passive (natural flushing) remediation, or active-engineered remediation. Selection is based on site characteristics and conditions. Initially, target strategies are proposed using a limited data set, matching the site conditions to the provisions in the standards. More than one strategy may be targeted based on knowledge of the site. Data gaps are identified, and additional site data are collected. The targeted strategy(ies) is (are) then confirmed or reselected. With this process, additional site characterization activities are focused on a particular remediation strategy(ies), thus avoiding the tendency to keep studying the site. This process also helps to avoid the tendency to focus on just one remedial action alternative too early, prior to having enough characterization data. Lessons learned from applying this process to initial sites include: (1) risks associated with using limited characterization data sets are typically manifested during the remedial construction phase; (2) targeting more than one strategy offsets the risk of a compliance strategy not suceeding; (3) different contaminants may require different compliance strategies; (4) the process requires built-in flexibility because each site is generally unique and parameters vary in degrees of freedom between sites, resulting in unique solutions; and (5) early stakeholder involvement is essential to gain buy-in of the final solution. Lessons learned are continually updated to incorporate experience and efficiencies.

THE RIO TINTO MINE A VOLUNTEER CLEAN-UP SUCCESS STORY

Underground copper mining at the Rio Tinto mine in northern Nevada commenced in 1932 and continued intermittently for approximately forty years. Since 1975 the site has been essentially inactive. Mine operations included placement of tailings generated from ore processing in the Mill Creek drainage. In 1993, due to concerns about environmental damage to surrounding surface waters, four of the previous owners and operators of the site jointly formed the Rio Tinto Working Group (RTWG) to remediate the site in cooperation with the State of Nevada, Department of Conservation and Natural Resource and the Division of Environmental Protection (NDEP). The Rio Tinto Working Group consists of the Atlantic Richfield Company, Cleveland Cliffs Iron Company, E.I. DuPont de Nemours and Company, and Cominco American Inc., The regulatory and technical approach taken by the RTWG to achieve their objective of proactively implementing remedial measures at the site, rather than following the CERCLA process, are discussed. The steps included preparing an 18-element remedial program to be completed at the site and negotiating an Administrative Order on Consent (AOC) with the State of Nevada, which included a deferral from EPA for listing of the site on the NPL list. By entering into a cooperative relationshipmore » with the NDEP and avoiding the CERCLA process, the Rio Tinto Working Group was able to fast track site investigation and remedial designs, leading to a timely start up of remedial construction activities.« less

Evaluation of previous remedial construction along the Duquesne Bluff

Abstract The Boulevard of the Allies is a major four lane roadway in Pittsburgh, Pennsylvania that is constructed atop a near vertical, 35 meter high rock slope known locally as the Duquesne Bluff. Stratigraphic relief observed on the bluff consists of alternating sequences of flat lying sedimentary deposits of sandstone, siltstone, shale, carbonaceous shale, claystone and limestone. Expsoure of alternating sequences of durable and less durable rock has resulted in differential weathering and the formation of precarious overhanging conditions. In the interest of motorist safety and roadway improvement, a major remedial program was undertaken by the Pennsylvania Department of Transportation (PennDOT) in the mid 1980s. Primary remedial activities included rock trimming, rock bolting, the construction of dental concrete buttressing for overhanging rock support and shotcrete slope facing to arrest continued weathering of less durable claystone and carbonaceous shale exposures. As part of a current roadway improvement project, PennDOT and their consultant, Gannett Fleming, Inc., are evaluating the performance of previous remedial construction and are developing preliminary alternatives for future remediation. This paper will discuss the slope geology, overall favorable performance of the previous remedial construction and unfavorable slope conditions that may have resulted from large scale trimming operations.

Stability analysis of rock slopes with the direct sliding blocks method

The Boulevard of the Allies is a major four lane roadway in Pittsburgh, Pennsylvania that is constructed atop a near vertical, 35 meter high rock slope known locally as the Duquesne Bluff. Stratigraphic relief observed on the bluff consists of alternating sequences of flat lying sedimentary deposits of sandstone, siltstone, shale, carbonaceous shale, claystone and limestone. Expsoure of alternating sequences of durable and less durable rock has resulted in differential weathering and the formation of precarious overhanging conditions. In the interest of motorist safety and roadway improvement, a major remedial program was undertaken by the Pennsylvania Department of Transportation (PennDOT) in the mid 1980s. Primary remedial activities included rock trimming, rock bolting, the construction of dental concrete buttressing for overhanging rock support and shotcrete slope facing to arrest continued weathering of less durable claystone and carbonaceous shale exposures. As part of a current roadway improvement project, PennDOT and their consultant, Gannett Fleming, Inc., are evaluating the performance of previous remedial construction and are developing preliminary alternatives for future remediation. This paper will discuss the slope geology, overall favorable performance of the previous remedial construction and unfavorable slope conditions that may have resulted from large scale trimming operations.

Evaluation of previous remedial construction along the Duquesne Bluff

Accurate quantification of roughness is important in modeling strength, deformability and fluid flow behaviors of joints. Self-affine fractals seem to have potential to represent rock joint roughness profiles. Both stationary and non-stationary fractional Brownian profiles (self-affine profiles) with known values of fractal dimension, D, and input standard deviation, σ, were generated. For different values of the input parameter of the roughness-length method (window size, w), D and another associated fractal parameter A were calculated for the aforementioned profiles. It was found that σ has no effect on calculated D. A range for w between 1 (length having about 10 roughness data points) and 20 (10% of the total profile length) was found to be highly suitable to estimate D with 10% error for roughness profiles having D between 1.3 and 1.7 and a length of 200 units. Results indicated that the given roughness-length methodology has the capability of producing accurate estimates for fractal parameters for both stationary and non-stationary profiles with a global linear trend. The estimated A was found to increase with both D and σ and seems to have potential to capture the scale effect of roughness profiles. The parameter combinations (a) D and A or (b) D and the cross-over length, are suggested to use with the roughness-length method to quantify stationary roughness. In addition, one or more parameters should be used to quantify the non-stationary part of roughness, if it exists. The calculated cross-over lengths of the profiles indicated the difficulty in measuring roughness heights of natural rock joints at measurement intervals comparable to the cross-over lengths of the profiles. The study showed the necessity to know the effect of input and profile parameter values on the estimated fractal parameters in order to calculate these parameters accurately.

Techniques for successfully implementing in‐situ remediation systems

AbstractAs the remediation industry rapidly matures, a greater emphasis is placed on providing on‐site remedies involving in‐situ soil and groundwater technologies. Selecting and implementing cost‐effective technologies requires a defined working process focused on integrating the relationship between the design engineer/scientist and the remedial contractor. This article briefly explores various contractual vehicles and their effect on the designer/contractor relationship and identifies preconstruction documents needed to initiate a remedial construction program. A detailed discussion is presented that describes the transition from remedial design to remedial construction and offers practical application of preconstruction, construction, and postconstruction techniques. Preconstruction techniques involve communication processes and procedures designed to reduce installation uncertainty, address constructability issues, promote value engineering alternatives, and reaffirm the project objectives. Construction techniques focus on effective ways to communicate and document problems and solutions encountered during construction activities. Postconstruction techniques describe ways to provide useful information that may have a continued effect on system performance or used to document the achievement of project goals.

Grouting in Difficult Soil and Weather Conditions

Several methods of soil grouting and conventional underpinning are used to stabilize subsoils and repair the foundations of three apartment buildings. Innovative cold weather compaction grouting techniques were used in difficult soil conditions to densify poorly compacted man‐placed fill and soft organic silts beneath building foundations. Penetration grouting using a Portland cement slurry and Pozzolan (flyash) is performed to reduce permeability of the upper subsoils and to fill ineffective and detrimental building perimeter drains. A gravel intrusion jacking method is used to further density upper soils in conjunction with conventional underpinning methods. The project is unique because: (1) Techniques were used that allowed the contractor to drill and densify loose fills and soft natural soils containing cobbles and boulders; (2) the contractor was able to perform grouting and underpinning under extremely adverse weather conditions by using special equipment; and (3) occupants were able to remain in buildings during remedial construction.